Referenced-based AC approaches, which build a VC model to transform reference utterances with the target accent from a source speaker to the target speakers, have been prevalent previously.
Phonetic posteriograms (PPG) is often utilized to achieve the goal of VC [1]}, [2]}.
But basic VC model is only applicable to seen speakers in AC. To generalize to unseen speakers, the speaker encoder has been introduced [3]} to extract a speaker embedding for unseen speakers at inference time.
To ease the requirement of reference at inference time, Li et al.  [4]} proposed a target-accent TTS system to generate reference speech at synthesis time.
